<?php
/**
 * Created by Alan.
 * User: Alan
 * Date: 2018\8\11 0011
 * Time: 21:45
 */

namespace app\api\service;

use app\lib\enum\ScopeEnum;
use app\lib\exception\TokenException;
use app\lib\exception\WeChatException;
use think\Exception;
use app\api\model\User as UserModel;

class UserToken extends Token
{
    protected $code;
    protected $wxAppID;
    protected $wxAppSecret;
    protected $wxLoginUrl;

    public function __construct($code)
    {
        $this->code = $code;
        $this->wxAppID = config('wx.app_id');
        $this->wxAppSecret = config('wx.app_secret');
        $this->wxLoginUrl = sprintf(config('wx.login_url'),$this->wxAppID,$this->wxAppSecret,$this->code);
    }

    public function get(){
        $result = curl_get($this->wxLoginUrl);
        $wxResult = json_decode($result, true);
        if(empty($wxResult)){
            throw new Exception('获取session_key及openID时异常，微信内部错误');
        }
        else{
            $loginFail = array_key_exists('errcode',$wxResult);
            if( $loginFail ){
                $this->processLoginError($wxResult);
            }
            else{
                return $this->grantToken($wxResult);
            }
        }

    }

    private function grantToken($wxResult){
        //拿到openid
        //查看数据库，当前openid是否已经存在
        //如存在，则不处理，如不存在，新增一条user数据
        //生成令牌，准备缓存数据，写入缓存
        //把令牌返回到客户端去
        $openid = $wxResult['openid'];
        $user = UserModel::getByOpenID($openid);
        if( $user ){
            $uid = $user->id;
        }
        else {
            $uid = $this->newUser($openid);
        }
        $cachedValue = $this->prepareCachedValue($wxResult,$uid);
        $token = $this->saveToCache($cachedValue);
        return $token;
    }

    private function saveToCache($cachedValue){
        $key = self::generateToken();
        $value = json_encode($cachedValue);
        $expire_in = config('setting.token_expire_in');
        $result = cache($key, $value, $expire_in);
        if( !$result ){
            throw new TokenException([
                'msg' => '服务器缓存异常',
                'errorCache' => 10005
            ]);
        }
        return $key;
    }

    private function prepareCachedValue($wxResult, $uid){
        $cachedValue = $wxResult;
        $cachedValue['uid'] = $uid;
        $cachedValue['scope'] = ScopeEnum::User;
        return $cachedValue;
    }

    private function newUser($openid){
        $user = UserModel::create([
            'openid' => $openid
        ]);
        return $user->id;
    }

    private function processLoginError($wxResult){
        throw new WeChatException([
            'msg' => $wxResult['errmsg'],
            'errorCode' => $wxResult['errcode']
        ]);
    }
}